1. Field of the Invention
This invention relates to a flashback structure of the type formed specifically on the base member attached to a proximal end of a hollow needle having a sharpened tip at the distal end thereof and further wherein the base and needle structure are primarily designed for the support and placement of a catheter assembly properly within a blood vessel. A fluid flow channel is formed in a circuitous configuration on the base and disposed and structured for visual observation of blood entry and travel along the flow channel wherein such proper flow is indicative of proper placement of the sharpened tip within the blood vessel, the latter being necessary for positioning of the catheter in the same blood vessel.
2. Description of the Prior Art
In the utilization of a catheter assembly to the extent of proper placement of the catheter assembly, the sharpened tip of the supporting needle or cannula on which the catheter structure is mounted first penetrates the designated blood vessel. When the sharpened tip is properly positioned, blood flows continuously through the hollow support needle from the tip to a proximal end thereof which is fixedly attached to a gripping base. The blood passing from the blood vessel through the needle will continue to flow into any receiving chamber or cavity. Such flow characteristics allows the medical personnel applying the catheter to visually observe the blood flow. If the flow is continuous, the user knows that the tip of the needle is properly positioned in a vein or artery and the catheter, coaxially disposed about the penetrating needle is ready for subsequent advancement into the vein or artery in which the needle tip has been properly positioned.
Visual observation of incoming blood flow is recognized as an efficient and proper means of determining whether the sharpened tip of a needle is positioned within the blood vessel of the patient. There is a need in the medical profession for what may be termed a flashback structure which is specifically designed to enhance or facilitate the visual observation of blood flow from the needle into the base or gripping portion of the catheter assembly. Such a flashback structure ideally should be capable of providing observation, not only of the initial start of blood flow, but the determination that the incoming blood is in a state of continuous flow as the blood passes from the proximal end of the catheter into the flashback structure. For example, in such instances where the sharpened tip passes completely through the blood vessel, there will be an initial flow of blood passing through the needle and into the leading end of the flashback structure or chamber. However, if the path of fluid flow of the blood entering the flashback chamber or cavity is not properly designed, visual observation to determine whether the blood flow is initial or continual may be difficult.
In the prior art, U.S. Pat. No. 4,365,630 to McFarlane discloses a flashback chamber providing a substantially circuitous path of blood flow as it enters the base of the flashback chamber. While efficient and operable for its intended function, the structure disclosed in the above noted patent may also be somewhat difficult and/or expensive to produce due to the relatively complex structure in forming the preferred circuitous path of blood flow used to enhance visual observation thereof.
The present invention relates to a flashback structure of a simplified design and construction yet which may facilitate visual observation of blood flow to the extent that determination of continuous blood flow is readily accomplished.